The present invention relates bumper systems designed for pedestrian safety, and more particularly to a bumper system with lower apron designed with specific features to reduce “apron caused” pedestrian leg injury during an impact, and also that is particularly designed to work in conjunction with an adjacent primary bumper system for optimal “coordinated” impact resistance (i.e. where the primary bumper system and apron combine to form a coordinated “complete” bumper system designed for reduced pedestrian leg injury).
Traditionally, bumper systems are designed to protect a vehicle and its occupants. Recently, vehicle manufacturers of passenger vehicles are designing vehicles for improved pedestrian safety. As vehicle designers began to consider pedestrian safety, the bumper systems were often designed to provide a “softer” initial impact (such as to produce a lower force of resistance during a first few centimeters of impact stroke) and/or were designed to cause the pedestrian to roll onto the vehicle's hood during an impact. However, improvements are desired to further reduce pedestrian injury.
Lower aprons below a primary bumper beam have been used in an attempt to reduce pedestrian leg injury. However, conflicting requirements make design of any such lower apron difficult. For example, the lower apron should preferably be sufficiently stiff to help prevent a pedestrian from being drawn under the vehicle during an impact. At the same time (using traditional thinking), the apron potentially should not be so strong as to unnecessarily injure the pedestrian upon impact from the apron itself. The apron must be strong enough and durable enough to avoid being unacceptably damaged and/or destroyed by contact with curbs and other low obstacles often encountered by a vehicle. Yet, the apron must not be so rigid and heavy/structural that it becomes damaged (or causes vehicle damage) upon impacting a road-level object, and also it must not add an unacceptable amount of weight to the vehicle, particularly in view of vehicle weight and mpg requirements and goals, keeping in mind that any mass located ahead of the front vehicle wheels can adversely affect vehicle stability and can have an amplified negative effect on vehicle stability and mpg.